1. Field of the Invention
The present invention is generally related to a compound with a carboxyl acid group and an amide group, and more particularly to a water-soluble compound with a carboxyl acid group and an amide group.
2. Description of the Prior Art
Recently, compounds with carboxyl acid group(s) having skin whitening effect are often applied in cosmetic products. For example, azelaic acid is a common cosmetic raw material and has anti-acne and whitening effect. However, it has poor solubility to cosmetic base materials and this affects skin penetration and thereby results in formulation difficulties.
In order to develop better cosmetic materials, the skin whitening effect and the solubility to cosmetic base materials should be considered simultaneously. Thus, many compounds with carboxyl acid group(s) are synthesized successively. However, their water solubility is still not satisfied while generally commercial whitening products are aqueous solutions. For example, it is not easy to use non-salt solid compound with carboxyl acid group(s) together with an aqueous solution. Therefore, non-salt solid materials have limited application fields and lack of convenience.
In order to resolve such a problem, solid salts become very important in development. For example, the patent WO2006/010590A1 disclosed a compound with carboxyl acid salts, comprising a structure of alpha-amino acid and non-toxic cation, where its water solubility is from ion dissociation. That is, while in use, solid raw materials should dissolve in solvent and then be blended with other cosmetic raw materials. Thus, solid raw materials can not be blended with other materials directly to thereby result in inconvenience.
At present, compounds with carboxyl acid group(s) are still under development since their water solubility is still not satisfied. In view of the above description, a novel water-soluble compound with carboxyl acid group(s) is urgently needed.